How does human evolution or natural selection relate to the susceptibility of disease

Imagine you are a geneticist interested in studying a newly discovered species of very colorful birds. you have found that a single gene is responsible for their beautiful colors and that yellow birds are homozygous for the yellow allele, blue birds are homozygous for the blue allele and green birds are heterozygous for these alleles. you focused your efforts on studying one specific population and counted 9% yellow, 49% blue and 42% green birds. what are the allele frequencies in this population? \